Systems for collecting surface floating matters in a clarifying tank generally operate in a scrapper-like fashion to bring floating matters close to collector channels and to bring heavy waste matters laying at the bottom of the tank into a collector drain. The mechanisms used for this purpose usually have an important drawback in that they stop on the surface at around 1.5 m (5 feet) from the collector channels, thereby leaving a dead zone where the floating matters aggregate to form a crust. The systems proposed to cure the aforesaid mechanisms of this problem are generally complex, with many partially or totally immerged mechanical components due to the limited space in which these systems are installed.
Known in the art are U.S. Pat. Nos. 3,831,767 (Lefur et al.); U.S. Pat. No. 3,872,017 (Bishop); U.S. Pat. No. 4,054,520 (McGivern); U.S. Pat. No. 4,470,905 (Pangburn et al.); U.S. Pat. No. 4,514,303 (Moore); U.S. Pat. No. 4,880,533 (Hondulas); U.S. Pat. No. 5,015,393 (Russell et al.); U.S. Pat. No. 5,035,681 (Hertel et al.); U.S. Pat. No. 5,047,151 (Brandkvist); U.S. Pat. No. 5,057,219 (Fujiwara); U.S. Pat. No. 5,165,522 (Uttke et al.); U.S. Pat. No. 5,242,600 (Meylor et al.); U.S. Pat. No. 5,250,178 (Casper et al.); U.S. Pat. No. 5,268,099 (Krofta et al.); U.S. Pat. No. 5,269,928 (Leikam); U.S. Pat. No. 5,336,417 (Hannum); U.S. Pat. No. 5,454,942 (Ljungberg); U.S. Pat. No. 5,538,631 (Yeh); U.S. Pat. No. 5,545,324 (Workman); U.S. Pat. No. 5,565,099 (Fauret et al.); Re. U.S. Pat. No. 35,668 (Albertson); U.S. Pat. No. 5,728,304 (Yeh); U.S. Pat. No. 5,788,837 (Hannum); U.S. Pat. No. 5,948,277 (Frankenberger); U.S. Pat. No. 5,968,353 (Herbert et al.); and U.S. Pat. No. 6,017,180 (Wilham); which show various sewage treatment devices and systems illustrating the state of the art.